This invention relates to a method and apparatus for penetrating ice, frozen soils and other low-melting solid materials, and more particularly to a thermochemical ice penetrator.
There are many situations in cold climates where it is desirable to penetrate ice cover. For instance, a small hole may be drilled through an ice sheet to determine the thickness of the sheet. It may also be desirable to penetrate an ice sheet for the purpose of carrying electrical, electronic, acoustic, or electroacoustic instrumentation into the ice or into the water beneath the ice sheet. It may furthermore be desirable to provide holes in an ice sheet for the attachment of anchors to anchor instrumentation packages, aircraft, light structures, etc. to ice or frozen soil.
Thermal drilling using steam or hot water is a welltried and effective method for drilling holes in ice. However, thermal drilling typically requires boilers and pumps of substantial size and weight together with cumbersome insulation around delivery lines. Thus, such a system is not adaptable to the production of a compact, autonomous penetrator required for deployment of small instrument packages.
It is also known to use thermochemical reactions for penetrating ice. One such system is described in Delgendre et al, Canadian Patent No. 977,737, issued Nov. 11, 1975. That patent shows a reactor tube containing a solid propellant which is ignited to produce a hot gas which is then directed against the ice through an outlet.
Eninger et al, U.S. Pat. No. 4,651,834 issued Mar. 24, 1987 describes another form of ice penetrating device in which the penetrator is in the form of an elongated body containing a solid mass of reactant which reacts with water and thereby melts and penetrates the ice. With this system, the reactant mass is consumed lengthwise of the body by its reaction with water, such that the maximum penetration distance of the device through the ice is determined by the length of reactant mass within the penetrator. It functions well only with lithium or lithium alloys as the reactant mass.
There remains a need for a penetrator which is compact, light-weight and simple to use while being highly efficient in penetrating ice with a wide variety of thermochemical reactants.